共查询到20条相似文献,搜索用时 44 毫秒
1.
Natasa Zabukovec Logar Gregor Mali Sanja Jevtic Amalija Golobic 《Journal of solid state chemistry》2010,183(5):1055-8710
A single-crystal X-ray diffraction analysis of an open-framework aluminophosphate ULM-3 Al prepared by 3-methylaminopropylamine (MAPA) as structure-directing agent revealed an orthorhombic Pcab symmetry (a=9.9949(4) Å, b=15.8229(7) Å, c=18.1963(5) Å, R=0.0648, Z=8, unit cell formula [Al24P24O96F16·C32H112N16]), which differs from the Pbc21 symmetry of the structural analogue prepared in the presence of 1,4-diaminobutane. The 27Al, 31P, 19F, 13C and 1H NMR investigations, which were performed to study in detail MAPA arrangement inside the framework as well as the interactions of MAPA with the aluminophosphate host, confirmed the crystal symmetry and the proposed hydrogen bonding scheme between the template and the framework. 相似文献
2.
L. F. da Silva M. I. B. Bernardi L. J. Q. Maia G. J. M. Frigo V. R. Mastelaro 《Journal of Thermal Analysis and Calorimetry》2009,97(1):173-177
This work reports on the synthesis of a SrTi1−x
Fe
x
O3 nanostructured compound (0.0 ≤ x ≤ 0.1) using a modified polymeric precursor method. The effect of the addition of iron on the thermal, structural and morphological
properties of the nanoparticles was investigated by FT-IR spectroscopy, X-ray diffraction, and field emission scanning electron
microscopy (FE-SEM). A thermogravimetric analysis indicated that the crystallization process preceded by three decomposition
steps. Differential thermal analysis experiments showed that decomposition occurred in a broad range of temperatures from
400 to 600 °C. It was observed that iron ions acted as catalysts, promoting rapid organic decomposition and phase formation
at a lower temperature than in SrTiO3. Moreover, the addition of iron decreased the crystallite size and increased the lattice parameter of the SrTi1−x
Fe
x
O3 structure. 相似文献
3.
Ar and Kr matrix effect on the geometry and Cl–H stretching (ν
s
(Cl–H)) and librational (ν
l
(Cl–H)) frequencies of the hydrogen-bonded complex Cl–H···NH3 are simulated within the framework of polarizable continuum model with integral equation formalism (IEF-PCM) at B3LYP and
MP2 levels of theory with the basis set 6-311++G(2df,2pd). Within the framework of B3LYP and IEF-PCM, the simulated gas phase,
Ar, and Kr matrix ν
s
(Cl–H) of the complex are 2140, 1684, and 1550 cm−1, respectively, which deviate from the experimental values (~2200, 1371, and 1218 cm−1) by −60, 313, and 332 cm−1. Within the framework of MP2 and IEF-PCM, the gas phase, Ar, and Kr matrix ν
s
(Cl–H) are calculated as 2366, 2037, and 1957 cm−1 by the harmonic approximation, and as 2177, 1876, and 1665 cm−1 by the full-dimensional anharmonic correction. The matrix effect modeling is of greater importance than the anharmonic correction
in accounting for the large experimental gas phase to Ar or Kr matrix shift of the ν
s
(Cl–H) (−829 or −982 cm−1). Our calculations do not support the assignment of the 733.8 and 736.9 cm−1 bands to the Ar and Kr matrix ν
l
(Cl–H). 相似文献
4.
H. X. Ma B. Yan Y. H. Ren Y. Hu Y. L. Guan F. Q. Zhao J. R. Song R. Z. Hu 《Journal of Thermal Analysis and Calorimetry》2011,103(2):569-575
3,3-Dinitroazetidinium (DNAZ) salt of perchloric acid (DNAZ·HClO4) was prepared, it was characterized by the elemental analysis, IR, NMR, and a X-ray diffractometer. The thermal behavior
and decomposition reaction kinetics of DNAZ·HClO4 were investigated under a non-isothermal condition by DSC and TG/DTG techniques. The results show that the thermal decomposition
process of DNAZ·HClO4 has two mass loss stages. The kinetic model function in differential form, the value of apparent activation energy (E
a) and pre-exponential factor (A) of the exothermic decomposition reaction of DNAZ·HClO4 are f(α) = (1 − α)−1/2, 156.47 kJ mol−1, and 1015.12 s−1, respectively. The critical temperature of thermal explosion is 188.5 °C. The values of ΔS
≠, ΔH
≠, and ΔG
≠of this reaction are 42.26 J mol−1 K−1, 154.44 kJ mol−1, and 135.42 kJ mol−1, respectively. The specific heat capacity of DNAZ·HClO4 was determined with a continuous C
p mode of microcalorimeter. Using the relationship between C
p and T and the thermal decomposition parameters, the time of the thermal decomposition from initiation to thermal explosion (adiabatic
time-to-explosion) was evaluated as 14.2 s. 相似文献
5.
Andrzej Mianowski Izabela Baraniec-Mazurek Rafał Bigda 《Journal of Thermal Analysis and Calorimetry》2012,107(3):1155-1165
For dehydration of CaC2O4·H2O and thermal dissociation of CaCO3 carried out in Mettler Toledo TGA/SDTA-851e/STARe thermobalance similar experimental conditions was applied: 9–10 heating rates, q = 0.2, 0.5, 1, 2, 3, 6, 12, 24, 30, and 36 K min−1, for sample mass 10 mg, in nitrogen atmosphere (100 ml min−1) and in Al2O3 crucibles (70 μl). There were analyzed changes of typical TGA quantities, i.e., T, TG and DTG in the form of the relative
rate of reaction/process intended to be analyzed on-line by formula (10). For comparative purposes, the relationship between experimental and equilibrium conversion degrees was used (for
P = P\ominus P = P^{{\ominus}} ). It was found that the solid phase decomposition proceeds in quasi-equilibrium state and enthalpy of reaction is easily
“obscured” by activation energy. For small stoichiometric coefficients on gas phase side (here: ν = 1) discussed decomposition
processes have typical features of phenomena analyzable by known thermokinetic methods. 相似文献
6.
H. M. Ye N. Ren H. Li J. J. Zhang S. J. Sun L. Tian 《Journal of Thermal Analysis and Calorimetry》2010,101(1):205-211
The complex of [Nd(BA)3bipy]2 (BA = benzoic acid; bipy = 2,2′-bipyridine) has been synthesized and characterized by elemental analysis, IR spectra, single
crystal X-ray diffraction, and TG/DTG techniques. The crystal is monoclinic with space group P2(1)/n. The two–eight coordinated Nd3+ ions are linked together by four bridged BA ligands and each Nd3+ ion is further bonded to one chelated bidentate BA ligand and one 2,2′-bipyridine molecule. The thermal decomposition process
of the title complex was discussed by TG/DTG and IR techniques. The non-isothermal kinetics was investigated by using double
equal-double step method. The kinetic equation for the first stage can be expressed as dα/dt = A exp(−E/RT)(1 − α). The thermodynamic parameters (ΔH
≠, ΔG
≠, and ΔS
≠) and kinetic parameters (activation energy E and pre-exponential factor A) were also calculated. 相似文献
7.
A. Migdał-Mikuli N. Górska E. Szostak 《Journal of Thermal Analysis and Calorimetry》2007,90(1):223-228
Phase transition and thermal decomposition of hexadimethylsulfoxidealuminium chloride were studied by differential scanning
calorimetry (DSC), thermogravimetry (TG) and simultaneous differential thermal analysis (SDTA). The gaseous products of the
decomposition were on-line identified by a quadrupole mass spectrometer (QMS). In the temperature range of 95–300 K, [Al(DMSO)6]Cl3 indicates one phase transition at T
ch=244.96 K (on heating) and at T
cc=220.87 K (on cooling). Large thermal hysteresis of the phase transition (∼24 K) indicates its first order character. Large
value of transition entropy (ΔS≈40 J mol−1 K−1) suggests its configurational character. Thermal decomposition of the title compound proceeds in four main stages. In the
first stage, which starts just above ca. 300 K, the compound loses two DMSO molecules per one formula unit and undergoes into
[Al(DMSO)4]Cl3. In the second stage, the next three DMSO ligands are released and simultaneously decomposed. The third stage, which continues
up to ca. 552 K, is connected with a loss of the last DMSO ligand and the formation of AlCl3. In the fourth stage AlCl3 reacts with carbon monoxide that originates from the decomposition of DMSO, and first aluminium oxychloride and next solid
Al2O3 plus carbon are created. 相似文献
8.
L. Tian N. Ren J. J. Zhang H. M. Liu S. J. Sun H. M. Ye K. Z. Wu 《Journal of Thermal Analysis and Calorimetry》2010,99(1):349-356
The two complexes of [Ln(CA)3bipy]2 (Ln = Tb and Dy; CA = cinnamate; bipy = 2,2′-bipyridine) were prepared and characterized by elemental analysis, infrared
spectra, ultraviolet spectra, thermogravimetry and differential thermogravimetry techniques. The thermal decomposition behaviors
of the two complexes under a static air atmosphere can be discussed by thermogravimetry and differential thermogravimetry
and infrared spectra techniques. The non-isothermal kinetics was investigated by using a double equal-double steps method,
the nonlinear integral isoconversional method and the Starink method. The mechanism functions of the first decomposition step
of the two complexes were determined. The thermodynamic parameters (ΔH
≠
, ΔG
≠
and ΔS
≠
) and kinetic parameters (activation energy E and the pre-exponential factor A) of the two complexes were also calculated. 相似文献
9.
Francisco C. C. Arantes Antonio C. Moro Iolanda S. Klein Cristiana da Silva Adelino V. G. Netto Antonio E. Mauro Vânia M. Nogueira 《Journal of Thermal Analysis and Calorimetry》2011,106(2):379-383
The synthesis, spectroscopic characterization, and thermal analysis of the compounds [Pd(X)2(mtu)(PPh3)] (X = Cl− (1), SCN− (2); mtu = N-methylthiourea; PPh3 = triphenylphosphine) and [Pd(X)2(phtu)(PPh3)] (X = Cl− (3), SCN− (4); phtu = N-phenylthiourea) are described. The thermal decomposition of the compounds occurs in two, three, or four stages and the final
decomposition products were identified as Pd0 by X-ray powder diffraction. The thermal stability order of the complexes is 4 > 3>2 > 1. 相似文献
10.
Swati Soman Yoshiki Iwai Junichi Kawamura Ajit Kulkarni 《Journal of Solid State Electrochemistry》2012,16(5):1761-1766
Li2O–Al2O3–TiO2–P2O5 (LATP) glass was fabricated by conventional melt quenching route. Glass transition temperature (T
g = 296 °C) and crystallization temperatures (T
C1,2) were obtained from thermal analysis. LATP glass was converted to glass–ceramic by heat treatment in the range 550–950 °C
for 6 h. X-ray diffraction analysis revealed LiTi2(PO4)3 as a major phase. Ionic conductivity increased monotonically with concentration, reaching a maximum of ~10−4 S/cm. AlPO4 phase was detected in samples heat-treated above 850 °C. Its presence decreased the conductivity, suggesting LiTi2(PO4)3 phase as main contributor to high ionic conductivity. NMR spectra confirmed the presence of mobile 7Li ions in the entire sample series and also gave some information on the structure and dynamics of conductivity. 相似文献
11.
M. M. Rao J. S. Liu W. S. Li Y. H. Liao Y. Liang L. Z. Zhao 《Journal of Solid State Electrochemistry》2010,14(2):255-261
Nano-Al2O3 was doped in poly(acrylonitrile-co-methyl methacrylate) (P(AN-co-MMA)), and polyethylene(PE)-supported P(AN-co-MMA)/nano-Al2O3 microporous composite polymer electrolyte (MCPE) was prepared. The performances of the prepared MCPE for lithium ion battery
use, including ionic conductivity, electrochemical stability, interfacial compatibility, and cyclic stability, were studied
by scanning electron spectroscopy, linear sweep voltammetry, and electrochemical impedance spectroscopy. It is found that
the nano-Al2O3 significantly affects the MCPE performances. Compared to the MCPE without any nano-Al2O3, the MCPE with 10 wt.% nano-Al2O3 reaches its best performances. Its ionic conductivity is improved from 2.0 × 10−3 to 3.2 × 10−3 S cm−1, its decomposition potential is enhanced from 5.5 to 5.7 V (vs Li/Li+), and its interfacial resistance on lithium is reduced from 520 to 160 Ω cm2. Thus, the battery performance is improved. 相似文献
12.
新型三维开放骨架磷酸铝化合物的合成及晶化过程中的共模板效应 总被引:1,自引:0,他引:1
以1,2-丙二胺(1,2-DAP)为结构导向剂,在180℃加热摩尔组成为n(Al_2O_3)∶n(P_2O_5)∶n(1,2-DAP)∶n(H_2O)=1∶6∶5.5∶139的初始混合物,合成了具有AlPO-CJ31骨架结构的新型三维开放骨架磷酸铝化合物(1);加热摩尔组成为n(Al_2O_3)∶n(P_2O_5)∶n(1,2-DAP)∶n(H_2O)=1∶6∶7.5∶139的初始混合物,合成了二维层状磷酸铝化合物APDAP_(12)-150.利用X射线粉末衍射分析(XRD)、元素分析、热重/差热分析等表征手段确认了化合物1的分子式为[Al_4P_5O_(20)·H_3O·H_2O]·[H_3NCH_2CHNH_3CH_3],质子化的水分子与双质子化的1,2-丙二胺共同起到了导向化合物1的作用.调变初始混合物中1,2-丙二胺的比例可显著影响其模板效应.1,2-丙二胺比例较低[n(1,2-DAP)=5.5]时,产物为三维开放骨架化合物,而当其比例较高[n(1,2-DAP)=7.5]时,产物为二维层状化合物. 相似文献
13.
K. M. Ibrahim I. M. Gabr G. M. Abu El-Reash R. R. Zaky 《Monatshefte für Chemie / Chemical Monthly》2009,100(1):625-632
Abstract
Acetone [N-(3-hydroxy-2-naphthoyl)] hydrazone (H2AHNH) has been prepared and its structure confirmed by elemental analysis and 1H NMR spectroscopy. It has been used to produce diverse complexes with Co(II), Ni(II), Cu(II), Zn(II), Cd(II), and U(VI)O2 ions. The complexes obtained have been investigated by thermal analysis, spectral studies (1H NMR, IR, UV–visible, ESR), and magnetic measurements. IR spectra suggest that H2AHNH acts as a bidentate ligand. The electronic spectra of the complexes and their magnetic moments provide information about geometries. The ESR spectra give evidence for the proposed structure and the bonding for some Cu(II) complexes. Thermal decomposition of the Ni(II) and Cu(II) complexes afforded metal oxides as final products. Kinetic data were obtained for each stage of thermal degradation of some of the complexes using the Coats–Redfern method. The formation of complexes in solution was studied pH-metrically and the order of their stability constants (log K) was found to be U(VI)O2 > Cu(II) > Zn(II) > Ni(II) > Cd(II) > Co(II). Antimicrobial and eukaryotic DNA studies were carried out. 相似文献14.
Yttrium
orthoborate crystallizes in the vaterite-type structure and has two polymorphous
forms, viz. a low- und a high temperature one. DTA measurements of YBO3
confirmed a reversible phase transition with a large thermal hysteresis. The
phase transition has been accurately characterized by the application of different
heating and cooling rates (β). Consequently, the extrapolation of the
experimental data to zero β yields the transition points at 986.9°C
for the heating up and at 596.5°C for the cooling down cycle. These values
correspond to samples just after treatment at 1350°C. For samples with
a different ‘thermal history’ other phase transition temperatures
are observed, (e.g. after having performed several heating and cooling cycles).
The linear relationship between the associated DTA signal ΔT=T
onset–T
offset and the square root
of the heating rate β was confirmed, but the relation between T
onset and square root of β
is not found here.
From the empirical data a good linear fitting
between T
onset and
ln(β+1) can be derived.
From the kinetic analysis (Kissinger
method) of the phase transformation of YBO3 an apparent
activation energy of about 1386 kJ mol–1
for heating and of about 568 kJ mol–1 for
cooling can be determined 相似文献
15.
D. Melo R. M. M. Marinho F. T. G. Vieira S. J. G. Lima E. Longo A. G. Souza A. S. Maia I. M. G. Santos 《Journal of Thermal Analysis and Calorimetry》2011,106(2):513-517
Perovskite type oxides have been intensively studied due to their interesting optical, electrical, and catalytic properties.
Among perovskites the alkaline earth stannates stand out, being strontium stannates (SrSnO3) the most important material in ceramic technology among them due to their wide application as dielectric component. SrSnO3 has also been applied as stable capacitor and humidity sensor. In the present work, SrSnO3:Cu was synthesized by polymeric precursor method and heat treated at 700, 800, and 900 °C for 4 h. After that, the material
was characterized by thermal analysis (TG/DTA), X-ray diffraction (XRD), infrared spectroscopy, and UV–vis spectroscopy. Results
indicated three thermal decomposition steps and confirmed the presence of strontium carbonate and Cu2+ reduction to Cu+ at higher dopant amounts. XRD patterns indicated that the perovskite crystallization started at 700 °C with strontiatite
(SrCO3) and cassiterite (SnO2) as intermediate phases, disappearing at higher temperatures. The amount of secondary phase was reduced with the increase
in the Cu concentration. 相似文献
16.
A. Zalga Z. Moravec J. Pinkas A. Kareiva 《Journal of Thermal Analysis and Calorimetry》2011,105(1):3-11
The preparation and characterization of the M′–M′′–O nitrate–tartrate (M′ = Ca, Ba, Gd and M′ = W, Mo) precursor gels synthesized
by simple, inexpensive, and environmentally benign aqueous sol–gel method is reported. The obtained gels were studied by thermal
(TG/DSC) analysis. TG/DSC measurements revealed the possible decomposition pathway of synthesized M′–M′′–O nitrate–tartrate
gels. For the synthesis of different metal tungstates and molybdates, the precursor gels were calcined at different temperatures
(650, 800, and 900 °C). According to the X-ray diffraction (XRD) analysis data, the crystalline compounds CaMo1-x
W
x
O4 doped with Ce3+ ions, BaMo1-x
W
x
O4 doped with Eu3+ ions and Gd2Mo3O12 were obtained from nitrate–tartrate gels annealed at 650–900 °C temperatures. The XRD data confirmed that the fully crystalline
single-phase powellite, scheelite, or Gd2(MoO4)3 structures were formed already at 650 °C. Therefore, the suggested sol–gel method based on the complexation of metal ions
with tartaric acid is suitable for the preparation of mixed tungstates–molybdates at relatively low temperature in comparison
with solid-state synthesis. 相似文献
17.
Diego M. Gil M. Carolina Navarro M. Cristina Lagarrigue J. Guimpel Raúl E. Carbonio M. Inés Gómez 《Journal of Thermal Analysis and Calorimetry》2011,103(3):889-896
The thermal decomposition of Y[Fe(CN)6]·4H2O has been studied in order to investigate the formation of the multi-ferroic oxide YFeO3. The starting material (Y[Fe(CN)6]·4H2O) and the decomposition products were characterized by IR spectroscopy, thermal analysis, X-ray powder diffraction (PXRD),
and scanning electron microscopy. Metastable YFeO3 with hexagonal structure, space group P6
3
/mmc, was obtained by thermal decomposition of Y[Fe(CN)6]·4H2O at 600 °C in air. Orthorhombic YFeO3 was obtained by the same method at T ≥ 800 °C in air. The crystal structure of orthorhombic YFeO3 was refined by Rietveld analysis using PXRD data. We found that it was slightly deficient in Y3+, which is in agreement with the small amount of Y2O3 found as impurity in the sample. The formula of the orthorhombic phase is Y0.986FeO3. 相似文献
18.
A complex of Erbium perchloric acid coordinated with l-aspartic acid and imidazole, Er2(Asp)2(Im)8(ClO4)6·10H2O was synthesized for the first time. It was characterized by IR and elements analysis. The heat capacity and thermodynamic
properties of the complex were studied with an adiabatic calorimeter (AC) from 80 to 390 K and differential scanning calorimetry
(DSC) from 100 to 300 K. Glass transition and phase transition were discovered at 220.45 and 246.15 K, respectively. The glass
transition was interpreted as a freezing-in phenomenon of the reorientational motion of ClO4− ions and the phase transition was attributed to the orientational order/disorder process of ClO4− ions. The thermodynamic functions [H
T
− H
298.15] and [S
T
− S
298.15] were derived in the temperature range from 80 to 390 K with temperature interval of 5 K. Thermal decomposition behavior
of the complex in nitrogen atmosphere was studied by thermogravimetric (TG) analysis and differential scanning calorimetry
(DSC). 相似文献
19.
P. O. Dunstan 《Journal of Thermal Analysis and Calorimetry》2009,97(2):755-760
The [InCl3(L)
n
] (where L is 2,2′-bipyridine (bipy), 2,2′-bipyridine N,N′-dioxide (bipyNO), N,N-dimethylacetamide (dma), urea (u), thiourea (tu) or 1,1,3,3-tetramethylthiourea (tmtu); n = 1.5, 3 or 4) were synthesized and characterized by melting points, elemental analysis, thermal analysis and IR spectroscopy.
The enthalpies of dissolution of the adducts, Indium(III) chloride and ligands in 1.2 M aqueous HCl were measured and by using
thermochemical cycles, the following thermochemical parameters for the adducts have been determined: the standard enthalpies
for the Lewis acid/base reactions (Δr
H
θ), the standard enthalpies of formation (Δf
H
θ), the lattice standard enthalpies (ΔM
H
θ), and the standard enthalpies of decomposition (ΔD
H
θ). 相似文献
20.
Thermal behavior of 1,2,3-triazole nitrate 总被引:1,自引:0,他引:1
Liang Xue Feng-Qi Zhao Xiao-Ling Xing Zhi-Ming Zhou Kai Wang Hong-Xu Gao Jian-Hua Yi Si-Yu Xu Rong-Zu Hu 《Journal of Thermal Analysis and Calorimetry》2011,104(3):999-1004
The thermal decomposition behaviors of 1,2,3-triazole nitrate were studied using a Calvet Microcalorimeter at four different
heating rates. Its apparent activation energy and pre-exponential factor of exothermic decomposition reaction are 133.77 kJ mol−1 and 1014.58 s−1, respectively. The critical temperature of thermal explosion is 374.97 K. The entropy of activation (ΔS
≠), the enthalpy of activation (ΔH
≠), and the free energy of activation (ΔG
≠) of the decomposition reaction are 23.88 J mol−1 K−1, 130.62 kJ mol−1, and 121.55 kJ mol−1, respectively. The self-accelerating decomposition temperature (T
SADT) is 368.65 K. The specific heat capacity was determined by a Micro-DSC method and a theoretical calculation method. Specific
heat capacity equation is
C\textp ( \textJ mol - 1 \text K - 1 ) = - 42.6218 + 0.6807T C_{\text{p}} \left( {{\text{J mol}}^{ - 1} {\text{ K}}^{ - 1} } \right) = - 42.6218 + 0.6807T (283.1 K < T < 353.2 K). The adiabatic time-to-explosion is calculated to be a certain value between 98.82 and 100.00 s. The critical
temperature of hot-spot initiation is 637.14 K, and the characteristic drop height of impact sensitivity (H
50) is 9.16 cm. 相似文献